Presence Of Erm Research Articles

Cystoid macular edema following repeat DMEK: incidence and risk factors.

To describe the incidence of CME in re-DMEK procedures and identify the associated risk factors. Retrospective case series of 88 patients who underwent re-DMEK surgeries from January 2013 to October 2023. Surgical results were analyzed based on the cause of corneal decompensation, associated ophthalmologic factors, occurrence of CME after primary DMEK surgery, incidence of CME after re-DMEK, time interval between surgery and onset of CME, and management and outcomes of CME. Primary DMEK indications were Fuchs endothelial corneal dystrophy (FECD) in 40 eyes (44.9%), PBK in 30 eyes (33.7%) and herpes simplex virus (HSV) in 10 eyes (11.2%). After the first DMEK surgery, CME occurred in 16 eyes (18%) with a mean interval of 23.4 ± 16.7weeks. After re-DMEK surgery, CME occurred in 22.5% with a mean interval of 14.2 ± 21.9weeks. It was a new onset in 13 eyes (65%), recurrent in 6 eyes (30%), and persistent in 1 eye (5%). On multivariate analysis, no significant association was found between the presence of ERM and CME following re-DMEK. Eyes with a history of PPV and prior CME were significantly associated with CME occurrence with odd ratios of 4.9 (95% CI: 1.04-23.1, p = 0.04) and 4.1 (95%CI: 1.2-13.5, p = 0.02) respectively. CME following re-DMEK occurs in 22.5% of cases, primarily within the first three months post-operatively. The main risk factors include a previous occurrence of CME after the initial DMEK and a history of PPV. However, CME does not seem to negatively impact the final visual outcomes of re-DMEK.

Molecular Characterization of Enterococcus faecium Clinical Isolates Harbouring erm (T) from an Italian Hospital.

The presence of erm(T) gene conferring resistance to macrolides, lincosamides and streptogramin B (MLSB), was screened in 296 enterococci collected from clinical samples in a central Italy hospital and seven Enterococcus faecium isolates resulted positive to erm(T) by PCR. All isolates were resistant to erythromycin, tetracycline, ciprofloxacin and ampicillin but susceptible to vancomycin and chloramphenicol. Whole Genome Sequencing analysis revealed that in five E. faecium isolates, all belonging to the sequence type ST80 included in the clonal complex CC17 responsible of nosocomial infections, erm (T) gene was chromosome-located, in different genetic contexts. In E. faecium 735,236, erm (T) was on a 4,159-bp region flanked by two IS1216 and inserted at the 3' end of the mp gene. In E. faecium 711,448 and 739,437, erm (T) was found in a 4,463-bp region identical to that detected in E. faecium 735,236 except for 319bp. In E. faecium 713,729 and 757,415, erm (T) was on a 7,038-bp region flanked by IS1251 and ISEfm2 transposases and encompassed between the genes encoding a recombinase and three hypothetical proteins. erm(T)-carrying minicircles were detected in all isolates by inverse PCR assays demonstrating that erm(T) was included in mobile elements. However, in conjugation assays by filter mating, the erm(T) transferability was unsuccessful. Although macrolides are not used to treat enterococcal infections, the resistance is nonetheless widespread. These antibiotics are critically important in human medicine, but only few studies focused on erm (T)-harbouring clinical enterococci. The emergence of erm (T)-mediated erythromycin resistance among enterococci, potentially transferable to other nosocomial pathogens, should be constantly monitored.

Characterization of group A streptococci causing invasive diseases in Sri Lanka.

Group A β haemolytic streptococcus (GAS) or Streptococcus pyogenes is a human pathogen that causes an array of infections, including pharyngitis, cellulitis, impetigo, scarlet fever, toxic shock syndrome, and necrotizing fasciitis. The present study characterizes 51 GAS isolates from invasive infections in Sri Lanka, focusing on resistance profiles, genetic determinants of resistance, and virulence markers. Isolates were tested for sensitivity to penicillin, erythromycin, clindamycin, and tetracycline. The presence of erm(A), erm(B), and mef(A) was detected in erythromycin-resistant isolates, while tet(M) was detected in the tetracycline-resistant isolates. PCR was used to identify SpeA, SpeB, SpeC, SpeF, SpeG, smez, and ssa as virulence markers. Selected GAS isolates were emm-typed using the updated CDC protocol. All 51 isolates were susceptible to penicillin. The number of isolates non-susceptible to erythromycin was 16. The commonest resistance determinant identified was erm(B) (11/16). Tetracycline non-susceptibility was found in 36 (70.6 %) isolates and 26 of them contained the tet(M) gene. Thirteen (25.5 %) isolates were resistant to both tetracycline and erythromycin, while 12 (23.5 %) isolates were sensitive to both antibiotics. The commonest virulence markers detected among the isolates were SpeB (44, 86.3 %), SpeG (36, 70.6 %), and SpeF (35, 68.6 %), while SpeJ (15, 29.4 %), SpeA (10, 19.6 %), and ssa (5,9.8 %) were less common. The emm types were diverse. In conclusion, the GAS isolates studied showed resistance to erythromycin and tetracycline, while retaining universal susceptibility to penicillin. Additionally, these isolates exhibited diverse genetic backgrounds, displaying varying patterns of virulence genes and emm types.

Long term intraocular pressure fluctuation and epiretinal membrane in patients with glaucoma or glaucoma suspect

Aims/Purpose: The associations between ERM and glaucoma were suggested in several studies. In an animal model undergoing intermittent IOP elevations, a reactive gliosis, a phenotype of ERM, was found in the optic nerve head. We investigated the association between intraocular pressure (IOP) fluctuation and idiopathic ERM in patients with glaucoma or glaucoma suspect.Methods: In this retrospective study, a total of 84 patients with glaucoma or glaucoma suspect were included. Among them, forty one patients had no ERM and forty three patients had ERM. Long‐term fluctuation of IOP was defined as the standard deviation (SD) of IOP at all visits. Patients were divided into two groups according to the median value of SD of IOP: the low IOP fluctuation group and high IOP fluctuation group. Among patients with available heart rate variability (HRV) data, the relationship between the HRV parameter and IOP fluctuation was analysed.Results: Patients with ERM was older and had higher IOP fluctuation and higher proportion of having history of cataract surgery and greater macular thickness (p = 0.018, 0.049, 0.013, < 0.001). The high IOP fluctuation group showed higher proportion of patients with ERM (62.5%) than the low IOP fluctuation group (36.4%, p = 0.028). In the multiple logistic analysis, higher IOP fluctuation group were associated with the presence of ERM (p = 0.047). Among patients with ERM, eyes with stage 3 or 4 ERM had worse visual field defects based on mean deviation than those with stage 1 or 2 ERM (p = 0.025). The high IOP fluctuation group showed higher level of low frequency HRV, an index of sympathetic cardiac control than the low IOP fluctuation group (p = 0.027). Intereye comparison in eyes with ERM and the fellow eyes without ERM, eyes with ERM (2.2 ± 0.9 mmHg) had higher fluctuation of IOP than those without ERM (2.0 ± 0.8 mmHg, p = 0.029).Conclusions: In conclusion, long‐term IOP fluctuation had the relevance to idiopathic ERM in patients with glaucoma or glaucoma suspect. In glaucoma patients with ERM, more advanced stage ERMs were associated with worse visual field damage. Further studies are needed to determine if long‐term IOP fluctuation affects the progression of glaucoma and ERM.

Risk Factors Associated with Cystoid Macular Edema among Patients Undergoing Primary Repair of Rhegmatogenous Retinal Detachment

To investigate predictors of the development and resolution of cystoid macular edema (CME) after rhegmatogenous retinal detachment (RRD) repair. Retrospective cross sectional study. Patients who underwent primary repair of uncomplicated RRD. Demographics, ophthalmic history, visual acuity, RRD features, time to development/resolution of CME, OCT characteristics of CME/epiretinal membrane (ERM), type of surgery, and treatments were collected. Logistic regressions were used to identify predictors of CME development and resolution. Predictors of CME development and resolution. A total of 708 eyes were included, of which 55 (7.8%) developed CME. Factors associated with an increased risk of CME development included total number of retinal detachment surgeries (odds ratio [OR] 1.66 [1.24-2.23], P < 0.001), prior intraocular surgery (OR 4.43 [1.19-16.51], P= 0.03), and presence of ERM after surgery (OR 4.49 [2.30-8.74], P < 0.001). Patients undergoing pars plana vitrectomy (PPV) were more likely to develop CME compared with patients undergoing scleral buckling (SB; OR 3.09 [1.18-8.10], P= 0.02). A longer average time to CME detection was associated with lower CME resolution (OR 0.94 [0.89-0.998], P= 0.04). In patients who developed an ERM postsurgically, those who developed CME after ERM had a lower rate of resolution compared with those who developed CME before ERM (P= 0.03). Cystoid macular edema may be more likely to develop in patients undergoing PPV than SB, those who underwent more surgeries for RRD repair, those who had prior intraocular surgery, or those who developed an ERM after RRD repair. Resolution of CME may be affected by the time to detection of CME and ERM development. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Increase of Macrolide-Resistance in Streptococcus pneumoniae Strains After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Lima, Peru.

Streptococcus pneumoniae upper respiratory infections and pneumonia are often treated with macrolides, but recently macrolide resistance is becoming an increasingly important problem. The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the National Immunization Program of Peru in 2015. This study aimed to evaluate the temporal evolution of macrolide resistance in S. pneumoniae isolates collected in five cross-sectional studies conducted before and after this vaccine introduction, from 2006 to 2019 in Lima, Peru. A total of 521 and 242 S. pneumoniae isolates recovered from nasopharyngeal swabs from healthy carrier children < 2 years old (2 carriage studies) and samples from normally sterile body areas from pediatric patients with invasive pneumococcal disease (IPD) (3 IPD studies), respectively, were included in this study. Phenotypic macrolide resistance was detected using the Kirby-Bauer method and/or MIC test. We found a significant increase in macrolide resistance over time, from 33.5% to 50.0% in carriage studies, and from 24.8% to 37.5% and 70.8% in IPD studies. Macrolide resistance genes [erm(B) and mef(A/E)] were screened using PCR. In carriage studies, we detected a significant decrease in the frequency of mef(A/E) genes among macrolide-resistant S. pneumoniae strains (from 66.7% to 50.0%) after introduction of PCV13. The most common mechanism of macrolide-resistant among IPD strains was the presence of erm(B) (96.0%, 95.2% and 85.1% in the 3 IPD studies respectively). Macrolide resistance was more common in serotype 19A strains (80% and 90% among carriage and IPD strains, respectively) vs. non-serotype 19A (35.5% and 34.4% among carriage and IPD strains, respectively). In conclusion, S. pneumoniae macrolide resistance rates are very high among Peruvian children. Future studies are needed in order to evaluate macrolide resistance trends among pneumococcal strains, especially now after the COVID-19 pandemic, since azithromycin was vastly used as empiric treatment of COVID-19 in Peru.

Factors associated with diabetic macular edema in patients with proliferative diabetic retinopathy.

To identify factors associated with diabetic macular edema (DME) and to characterize the types of DME present in eyes with proliferative diabetic retinopathy (PDR). Observational, retrospective case series of PDR patients reviewed for demographic information, general medical history, ophthalmologic history, optical coherence tomography (OCT), and fluorescein angiogram image characteristics. DME and vitreomacular interface (VMI) status were determined using OCT images. DME was defined as center-involving DME (CI-DME) and noncenter-involving DME (NCI-DME). VMI was defined as vitreomacular adhesion (VMA), vitreomacular traction (VMT), or macular posterior vitreous detachment (PVD). A total of 293 eyes of 210 screened patients with PDR were included. Of the eyes, 194/293 (66.2%) had DME, and 99/293 (33.8%) had no DME; in univariable analysis, there were no significant differences in VMI status (p = 0.4) or epiretinal membrane (ERM, p = 0.1) between them. Of 194 eyes with DME, 90/194 (46.4%) had CI-DME, and 104/194 (53.6%) had NCI-DME. In univariable analysis, CI-DME eyes were significantly more likely than NCI-DME eyes to have a PVD (p = 0.029) and ERM (p < 0.001). In multivariable analysis, the presence of younger age (p = 0.028) and presence of ERM (p = 0.001) were significantly more likely to be observed in eyes with CI-DME. In this exploratory study focused on diabetic patients with PDR, we determined that VMI status did not have a significant association with DME in general, but VMI status, younger age, and presence of ERM may be associated with CI-DME.

Erm(T)-Mediated Macrolide-Lincosamide Resistance in Streptococcus suis.

ABSTRACTTo investigate the presence and location of erm(T) in clinical Streptococcus suis isolates and explore the transmission ability and fitness cost of erm(T)-carrying mobile genetic elements among S. suis isolates, MICs were determined by broth microdilution. The presence of erm(T) in S. suis was detected by PCR. The genetic environment of erm(T) in S. suis was explored by whole-genome sequencing (WGS) analysis. Intraspecies and interspecies transmission were examined by electrotransformation. The fitness cost associated with the carriage of an erm(T)-harboring plasmid or an integrative and conjugative element (ICE) was examined by competition experiments. Of 237 nonduplicate strains, erm(T) was detected in 2 S. suis strains (SC262-ST954 and SC117-ST1314), with its location on a 5,125-bp plasmid in S. suis SC262 and on a 64,013-bp ICESsuSC117 in S. suis SC117, respectively. Both the erm(T)-carrying plasmid pSC262 and the ICESsuSC117 were transmissible by transformation. Plasmid pSC262 can replicate and express macrolide-lincosamide resistance in heterologous hosts, including S. aureus and S. pneumoniae. Both the erm(T)-carrying plasmid and the ICE posed a fitness cost to the host S. suis isolate. To the best of our knowledge, this is the first report of the macrolide-lincosamide-streptogramin B resistance gene erm(T) in S. suis. Its location on a plasmid or an ICE will aid in its transmission. The low detection rate of erm(T) gene among the S. suis population might be due to the fitness cost of the erm(T)-carrying plasmid and ICE.IMPORTANCE Macrolide and lincosamide resistance due to the presence of erm(T) have posed a challenge for the treatment of Gram-positive pathogens. Although the low detection rate of erm(T) gene among the S. suis population due to the fitness cost of the erm(T)-carrying plasmid and ICE, the presence of erm(T) in S. suis and its potential transmission to other Gram-positive pathogens will be of important significance.

Whole genome sequence based capsular typing and antimicrobial resistance prediction of Group B streptococcal isolates from colonized pregnant women in Nigeria

BackgroundStreptococcus agalactiae (Group B Streptococcus, GBS) is one of the major bacterial pathogens responsible for neonatal sepsis. Whole genome sequencing has, in recent years, emerged as a reliable tool for capsular typing and antimicrobial resistance prediction. This study characterized vaginal and rectal isolates of Group B Streptococcus obtained from pregnant women in Port Harcourt, Nigeria using a whole-genome sequence-based approach.ResultsCapsular types Ia, Ib, II, III, IV and V were detected among the 43 isolates sequenced. Twelve sequence types (STs) were identified, with ST19 (n = 9, 27.3 %) and ST486 (n = 5, 15.2 %) the most frequent among non-duplicated isolates. Of the alpha-like proteins (alp) identified, Alp1 was the most prevalent in 11 (33.3 %) isolates. Macrolide and lincosamide resistance determinants were present in 15 (45.5 %) isolates; ermB was detected in 1 (3 %), ermTR in 7 (21.2 %) isolates, lnu gene was detected in 6 (18.2 %) and mef was identified in 3 (9.1 %) isolates. Resistance of GBS to erythromycin and clindamycin (predicted from presence of erm or mef genes) was found to be 30.3 % and 24.2 %, respectively. All isolates were predicted resistant to tetracycline with only the tetM gene identified. Fluoroquinolone-resistance conferring substitutions in gyrA + parC were detected in 9 (27.3 %) isolates and chloramphenicol resistance was predicted from presence of aac6’-aph2 gene in 11 (33.3 %).ConclusionsThe data available from the whole genome sequencing of these isolates offers a small but insightful description of common serotypes and resistance features within colonizing GBS in Nigeria.

Ethidium bromide exposure unmasks an antibiotic efflux system in Rhodococcus equi.

This study introduces a newly created strain (Rhodococcus equiEtBr25) by exposing R. equi ATCC 33701 to ethidium bromide (EtBr), a substrate for MDR transporters. Such an approach allowed us to investigate the resulting phenotype and genetic mechanisms underlying the efflux-mediated resistance in R. equi. R. equi ATCC 33701 was stimulated with increasing concentrations of EtBr. The antimicrobial susceptibility of the parental strain and R. equiEtBr25 was investigated in the presence/absence of efflux pump inhibitors (EPIs). EtBr efflux was evaluated by EtBr-agar method and flow cytometry. The presence of efflux pump genes was determined by conventional PCR before to quantify the expression of 30 genes coding for membrane transporters by qPCR. The presence of erm(46) and mutations in 23S rRNA, and gyrA/gyrB was assessed by PCR and DNA sequencing to exclude the occurrence of resistance mechanisms other than efflux. R. equi EtBr25 showed an increased EtBr efflux. Against this strain, the activity of EtBr, azithromycin and ciprofloxacin was more affected than that of rifampicin and azithromycin/rifampicin combinations. Resistances were reversed by combining the antimicrobials with EPIs. Gene expression analysis detected a marked up-regulation of REQ_RS13460 encoding for a Major Facilitator Superfamily (MFS) transporter. G→A transition occurred in the transcriptional repressor tetR/acrR adjacent to REQ_RS13460. Exposure of R. equi to EtBr unmasked an efflux-mediated defence against azithromycin and ciprofloxacin, which seemingly correlates with the overexpression of a specific MFS transporter. This genotype may mirror an insidious low-level resistance of clinically important isolates that could be countered by EPI-based therapies.

Identification of the first erm(B)-positive Campylobacter jejuni and Campylobacter coli associated with novel multidrug resistance genomic islands in Australia

ObjectivesThis report describes the first identification of two Campylobacter isolates harbouring erm(B) in Australia. MethodsTwo erm(B)-positive isolates, Campylobacter coli 18V1065H1 and Campylobacter jejuni 19W1001H1, were isolated from diarrhoeal faecal samples from two travellers who had recently returned from Southeast Asia. Isolates underwent whole-genome sequencing using an Illumina NextSeq system and were analysed with the Nullarbor pipeline. Antimicrobial resistance genes were identified using AMRFinderPlus and sequence types (STs) were determined by multilocus sequence typing and the PubMLST Campylobacter jejuni/coli typing scheme. ResultsBesideserm(B), C. jejuni 19W1001H1 possessed six other resistance genes [aad9, aadE, aph(3ʹ)-Illa, blaOXA-185, catA13 and tet(O)], the gyrA T86I mutation and the RE-CmeABC multidrug efflux pump variant. Campylobacter coli 18V1065H1 also possessed six resistance genes [aad9, aadE, aph(3ʹ)-IIIa, blaOXA-61, sat4 and tet(O)] in addition to erm(B); however, this isolate lacked genetic evidence for resistance to fluoroquinolones (no gyrA mutation). The erm(B) locus differed between isolates and neither was identical to previously identified erm(B) multidrug resistance genomic island (MDRGI) types. Both erm(B)-bearing isolates belonged to novel sequence types: ST9967 (C. jejuni 19W1001H1) and ST10161 (C. coli 18V1065H1). ConclusionsThis study detected the presence oferm(B) in Campylobacter for the first time in Australia. This novel mechanism of macrolide resistance is a major concern both for human and animal health and warrants close surveillance as macrolides are often the drug of choice for treating campylobacteriosis. The erm(B) gene is associated with several MDRGIs and dissemination of this resistance mechanism will likely limit treatment options for Campylobacter infections.

Point Deletion or Insertion in CmeR-Box, A2075G Substitution in 23S rRNA, and Presence of erm(B) Are Key Factors of Erythromycin Resistance in Campylobacter jejuni and Campylobacter coli Isolated From Central China.

Campylobacter jejuni and Campylobacter coli are major food-borne pathogens that cause bacterial gastroenteritis in humans, and poultry is considered as their most important reservoir. Macrolides, such as erythromycin, are the first-line choice for treatment of campylobacteriosis. In this study, of the 143 Campylobacter isolates recovered from poultry in central China during 2015–2017, 25.2% were erythromycin resistant. A2075G substitution in 23S ribosomal RNA (rRNA) and ribosomal methylase encoded by erm(B) were found in 4.2 and 4.9% isolates, respectively, and correlated with erythromycin resistance. The polymorphisms of CmeR-Box were also analyzed in our isolates. Among them, 9.1% isolates harbored a point deletion or insertion within the CmeR-Box, and we first showed that point deletion or insertion, but not substitution, in CmeR-Box led to high expression of cmeABC, which was significantly associated with erythromycin resistance (p < 0.05). These results suggest that point deletion or insertion in CmeR-Box, A2075G substitution in 23S rRNA, and presence of erm(B) are three main factors to erythromycin resistance in C. jejuni and C. coli.

2429. Whole-genome Sequencing of Healthcare-Onset C. difficile Infection (HO-CDI) Cases Shows Widespread Presence of Antimicrobial Resistance Genes

Background Clostridioides difficile infection (CDI) is the most common pathogen to cause healthcare-associated infections. Unlike some other bacterial pathogens antimicrobial treatment is seldom based on culture with susceptibility testing with infrequent surveillance for antimicrobial resistance. We have evaluated healthcare-onset CDI (HO-CDI) for both transmission and antimicrobial resistance emergence.MethodsWe identified cases of HO-CDI diagnosed by PCR within a 3 month period (October 1/2018–December 31/2018) at University of Virginia Health System with overlapping stays in the same inpatient units with other HO-CDI. Chart review of all cases was performed. C. difficile was cultured from stool, then DNA was extracted and underwent sequencing on Illumina Miseq platform. Antimicrobial resistance genes were screened using NCBI’s AMRFinder tool from the de-novo assembled contigs using SPAdes. All the C. difficile isolates underwent antibiotic susceptibility testing.ResultsEleven patients were identified with overlapping stays from 5 units. Mean age was 64 years and 63.6% were female. 36.3% of cases were severe CDI with one case of fulminant CDI. There was one recurrence within 90 days (9.1%). Patients were treated with PO vancomycin (72.7%) or IV metronidazole and PO vancomycin (27.3%), none were treated with metronidazole alone. None of the hospital strains were genetically related. There were two isolates with binary toxin gene (cdtB), one ribotype 027 (CD196) and one ribotype 078 (M120). Ninety-one percent of isolates had vanG-like gene cluster and vanZ1 originally identified in Enterococcus sp. erm(B), tet(M), and cfr(C) genes were also detected in several strains. All isolates were susceptible to vancomycin, metronidazole, and tigecycline. There was one strain with moxifloxacin resistance associated with the presence of erm(B) gene. None of the isolates were susceptible to clindamycin.ConclusionThere were no widely circulating clones or direct transmissions found in this small sample of HO-CDI cases at our hospital. Like others have we demonstrate carriage of many vanG/Z genes without conferring phenotypic resistance to vancomycin. The origin and function of Van genes in C. difficile could be an area of future research.Disclosures All authors: No reported disclosures.

855. Evolution of Group B Streptococcal Capsular Type V Invasive Infections in Neonates and Young Infants: A Whole Genome Sequencing Study

BackgroundSince 1970 group B Streptococcus (GBS) has been a frequent cause of sepsis or meningitis in young infants. Capsular polysaccharide type V was first recognized in 1990 and has increased to the point where it now causes ~15% of GBS infections. GBS type V strains are almost entirely sequence type 1 (ST1) in adult infections. To understand the emergence of type V GBS, we compared infant strains before 1990 to more contemporary isolates from young infants and adults.MethodsThirty-five strains isolated from blood or CSF of infants <90 days of age (Houston, 1979–1996) were compared with the following previously sequenced type V, ST1 strains: (1) 14 from infant blood or CSF from Center for Disease Control and Prevention (CDC) (2015–2017), (2) 193 blood ST1 isolates from adults (Houston, 1992–2013), and (3) 516 invasive isolates from the CDC (2015–2017). Isolates were sequenced using an Illumina MiSeq instrument followed by molecular typing, antimicrobial resistance gene determination, and phylogenetic analysis. Antimicrobial susceptibility testing (AST) was performed using disk diffusion and E-test.ResultsThe majority (29/35) of Houston young infant strains were ST1. Type V GBS strains isolated prior to 1990 were more likely to be of ST-2 or ST-26 (5/10) compared with those from 1990 or later (24/25 and 14/14 CDC infant invasive type V). Tetracycline resistance was identified in 83% (29/35) while macrolide resistance (MR) occurred in only 23% (8/35) of the strains. Compared with early neonatal isolates, MR was significantly more frequent among contemporary neonatal (12/14, 86%, P < 0.0001) and adult (502/710, 71%, P < 0.0001) ST1 GBS. Phylogenetic analysis showed two distinct clades defined, in part, by MR. A high-frequency MR (340/360, 94%) clade was defined by the presence of erm(B) on Tn3872 while the low-frequency MR clade (159/350, 45%) was more diverse in mobile elements contributing to MR. The majority (27/29) of early neonatal ST1 GBS strains were observed in the low-frequency MR clade.ConclusionInfant invasive disease due to type V GBS before 1990 consisted of more diverse STs but is now almost exclusively ST1. Differences in the frequency of MR between early neonatal and contemporary type V ST1 GBS suggest MR may, at least in part, have driven the expansion of type V ST1 GBS.Disclosures All Authors: No reported Disclosures.

Lack of correlation between reduced outpatient consumption of macrolides and macrolide resistance of invasive Streptococcus pneumoniae isolates in Slovenia during 1997-2017.

The objective of this study was to investigate the correlation between decreased national consumption of macrolides and resistance of invasive Streptococcus pneumoniae isolates in Slovenia during 1997-2017. A total of 4241 invasive S. pneumoniae isolates were collected in Slovenia from 1997 to 2017. The presence of erm(B), mef(E), mef(A) and erm(TR) genes was determined by PCR in 612 erythromycin-resistant isolates. Selected isolates carrying the mef(A) gene were further examined by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) was performed for 161 erythromycin-resistant isolates from 2004 to 2009. Consumption of macrolides decreased by 42.5% between 1997 and 2017, and by 57.0% from the highest consumption during 1999 to 2017. Resistance of S. pneumoniae increased by 120.7% in the same period, from 5.8% in 1997 to 12.8% in 2017. The most prevalent serotypes among macrolide-resistant isolates were 14 (54.9%), 19A (9.0%), 19F (8.3%), 6B (7.2%), 6A (5.2%) and 9V (19; 3.0%). The most prevalent determinant of macrolide resistance in the observed period was erm(B) (43.0%; 263/612), followed by mef(A) (36.3%; 222/612) and mef(E) (14.9%; 91/612). During the study period, an increasing trend in serotype 14, mef(A)-carrying isolates was observed, with a peak in 2011 (P<0.001); 63/71 isolates (88.7%) with the mef(A) gene were clonally related and were related to the international England14-9 clonal cluster. The reason for the observed increase in macrolide resistance among invasive S. pneumoniae in Slovenia despite decreased macrolide consumption was spread of the England14-9 clonal cluster.

Reinstating Mycobacterium massiliense and Mycobacterium bolletii as species of the Mycobacterium abscessus complex.

TheMycobacterium abscessus complex is a group of rapidly growing, multiresistant mycobacteria previously divided into three species. Proposal for the union of Mycobacterium bolletii and Mycobacterium massiliense into one subspecies, so-called M. abscessus subsp. massiliense, created much confusion about the routine identification and reporting of M. abscessus clinical isolates for clinicians. Results derived from multigene sequencing unambiguously supported the reinstatement of M. massiliense and M. bolletii as species, culminating in the presence of erm(41)-encoded macrolide resistance in M. bolletii. Present genome-based analysis unambiguously supports the reinstatement of M. massiliense and M. bolletii as species after the average nucleotide identity values of 96.7 % for M. abscessus versus M. bolletii, and 96.4 % for M. abscessus versus M. massiliense, and the 96.6 % identity between M. bolletii and M. massiliense was put into the perspective of a larger, 28-species analysis. Accordingly, DNA-DNA hybridization values predicted by the complete rpoB gene sequencing analysis were between 68.7 and 72.3 % in this complex. These genomic data as well as the phenotypic characteristics prompted us to propose to reinstate the previously known M. massiliense and M. bolletii into two distinct species among the M. abscessus complex.

Chloroquine inhibits Rhodococcus equi multiplication in murine (J774A.1) and foal alveolar macrophages

presence of erm(46) as detected by PCR in 124 isolates of R. equi. Expression of erm(46) in a macrolide-susceptible strain of R. equi induced high level resistance to macrolides, lincosamides, and streptogramins B, but not to other classes of antimicrobial agents. Transfer of erm(46) from resistant to susceptible strains of R. equi was confirmed and occurred at a transfer frequency of up to 2 10-3. This is the first molecular characterization of macrolide, lincosamides and streptogramins B resistance in R. equi. Resistance is caused by a novel erm gene, erm(46), which is transferrable likely by conjugation.

Novel transferableerm(46) determinant responsible for emerging macrolide resistance inRhodococcus equi

The objective of this study was to identify the molecular mechanism of macrolide resistance in the actinomycete Rhodococcus equi, a major equine pathogen and zoonotic agent causing opportunistic infections in people. Macrolide-resistant (n = 62) and macrolide-susceptible (n = 62) clinical isolates of R. equi from foals in the USA were studied. WGS of 18 macrolide-resistant and 6 macrolide-susceptible R. equi was performed. Representative sequences of all known macrolide resistance genes identified to date were used to search the genome assemblies for putative homologues. PCR was used to screen for the presence of the identified resistance determinant in the rest of the isolates. Mating experiments were performed to verify mobility of the gene. A novel erm gene, erm(46), was identified in all sequenced resistant isolates, but not in susceptible isolates. There was complete association between macrolide resistance and the presence of erm(46) as detected by PCR screening of all 124 clinical isolates of R. equi. Expression of erm(46) in a macrolide-susceptible strain of R. equi induced high-level resistance to macrolides, lincosamides and streptogramins B, but not to other classes of antimicrobial agents. Transfer of erm(46) to macrolide-susceptible R. equi was confirmed. The transfer frequency ranged from 3 × 10(-3) to 1 × 10(-2). This is the first molecular characterization of resistance to macrolides, lincosamides and streptogramins B in R. equi. Resistance was due to the presence of a novel erm(46) gene mobilizable likely by conjugation, which has spread among equine isolates of R. equi in the USA.

Acquired macrolide resistance genes in Haemophilus influenzae?

The objective of this study was to determine the prevalence of specific acquired macrolide resistance genes previously reported as present in clinical isolates of Haemophilus influenzae. A collection of 172 clinical respiratory isolates of H. influenzae, including 59 isolates from cystic fibrosis patients and 27 from non-cystic fibrosis bronchiectasis patients with significant prior macrolide use, was established. This collection was tested for azithromycin susceptibility using Etest and screened for the presence of erm(A), erm(B), erm(C), erm(F), mef(A) and mef(E) using locked nucleic acid dual-labelled hydrolysis probes. The azithromycin MICs ranged from 0.09 to >256 mg/L, with 2 (1.2%) isolates susceptible, 163 (94.8%) intermediate and 7 (4%) resistant according to EUCAST breakpoints (susceptible, ≤0.12 mg/L; resistant, >4 mg/L). None of the acquired macrolide resistance genes erm(A), erm(B), erm(C), erm(F), mef(A) or mef(E) was detected in any of the isolates. The specific acquired macrolide resistance genes are not widespread in H. influenzae and the high prevalence of these genes previously reported might be unique to the specific circumstances of that study.

Increase in the rate of azithromycin-resistant Streptococcus pneumoniae isolates carrying the erm(B) and mef(A) genes in Taiwan, 2006-2010.

BackgroundThis study investigated the molecular characteristics of azithromycin-resistant Streptococcus pneumoniae in Taiwan.MethodsA total of 486 non-duplicate isolates of azithromycin-resistant S. pneumoniae recovered from various clinical sources of patients treated at 22 different hospitals in Taiwan from 2006 to 2010. The presence of erm(B) and mef(A) genes using duplex PCR, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis of these isolates were studied.ResultsOf the isolates tested, 59% carried the erm(B) gene, 22% carried the mef(A) gene, and 19% carried both genes. The prevalence of isolates carrying the erm(B) and mef(A) genes increased from 10% (11/110) in 2006 to 25% (15/60) in 2010 (p-value = 0.0136). The majority of isolates carrying both erm(B) and mef(A) genes belonged to serotypes 19 F (64%) followed by 19 F A (24%). Of these isolates, 33% were sequence type 320 (ST320), 32% were ST236, and 12% were ST271.ConclusionsThe increase in incidence of mef(A)/erm(B)-positive azithromycin-resistant S. pneumoniae isolates during the study period was primarily due to serotypes 19 F and 19A and ST236 and ST320.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0704-z) contains supplementary material, which is available to authorized users.